Multiple-standard micrometer



Apnl 14, 1925. Y

L.. C. CRESCIO IULTIPLE STANDARD IIICROIIETER Filed Sevpt. 14, 1921 1 sss whlbar/komm? CIU/icio.,

Patented Apr. 14, 1925.

UNITED STATES 'PATENT orifice.

Louis o. onnsoro, or New Youn, N. Y., essronon. or onu-HALF fro Louis nienfirnsrA, or New Youn, u. Y.

MULTIPLE-STANDARD rrronoiitiernn.

Application tiled September 14, 1921. Serial No, 500,676.

To zZZ whom it 'may concern:

Be it 1irnown thut l, Lotus C. Cruise/1o, a citizen ot the United States, und resident of 7 Sixth Avenue, New York city, in the county ot New York und State ot New York, have invented certain :new und useful lmprovements in lMlultiple.-St:uiclurd Micrometers, of which the following` is u specification. i

This in\'fention relates to micrometers in general, und particularly to the kind adopted for taking simultaneous readings in vurious standards.

In order to understand the principle ot my invention, u general explanation of` the workingot a micrometer is necessary. h'licrometers mode today are usuullyv mode to reudin one standard, for instance, inches or millimeters, und to this end the pitch ot the screw thrend of the micrometer spindle is, in inch micrometers d0 to un inch, while in millimeter n'iicii'oinetersj, thepitch is one millimeter. Consequently the graduation tor inches corresponds with the pitch ot' the screw, that means that there ore 4:0 divisions to un inch. Thus, through one complete revolution'oit the spindle, the lutter moves longitudinally 1/-l0 or .025 of un inch.

The gruduntion on the thimlole ot nu inch micrometer is divided into ports circum terentiullY, und hy rotating?,` the thimhle Jfrom one ot .its merlis to the next, the spindle moves longritudinull7 l/25 of .025, in otherwords, .001 ot un inch. Then it ro` tutes to the second dirision, the spindle moves .002 ot' an'inch etc. Thus when the thimhle rotates u complete revolution or 360 degrees, the spindle has moved .025 or 1/-t0 ot un inch.

fit1

lu order to tulle the readings in :in ordinary inch micrometer, the longitudinal graduationA oit the barrel or sleeve not covered hv the thiinhle of the micrometer is multiplied hy 25, und edded to the product is the readingv teken from vthe thimble gruduotion.

ln millinietermicrometers :is usedtodnfy', the graduation of the thimhle is either in hundredths or other decimulso't u millimeter, thus the reudings'ore teken directthat meu-ns--to the number ot inillimeters not covered by the thimhle ot the micrometer is added the reading `from the thimhle which represents decimals ot uy millimeter.

fr The present invention `represents :i com ducted.

binzition oit inch 'and millimeter gruduations upon the sleeve or borrel withv u single graduation uponthe thimlole, co-operating` with the longitudinal `groduuticnfis.`

ln order to ohtuin the proper results, I have provided instead of u millimeter pitch or a .025 inch pitch for the screw thread ot the spindle, on exact l/2 millimeter pitch; that means l have divided :in inch into 50. partsless a. traction' ot .e of u millimeter. Thus the grzidustions do not rep-resent really` one jtull inch, und the inch readings would he inaccurate it I would not provide o compensitting` coleiiicient, which'is used in computing; inch readings.

rlhe correct division ot un inch into 50 parts expressed in millimeter' equivalent would he .508 millimeter. Now the l/50 `part ot' un inch represents .020 thereof.

ing; factor or co-eiiicient, whichis to loe suh-l trocted 'from euch reading,- on the inch graduation for euch single subdivision.

For exemple, it the thimhle o'l" a micrometer would leave visible 25 inch infuduutions oi' the longitudinal seule on the borrel, the

readings, irrespective of the thimhle readings, would he 25 times .020, giving .5 ofen inch, which reudinogwould be correct it each 50 divisionswould he .508 of e. millimeter. Since, however, the division is .5 oi u millimeter, the actual inch readings, are shorter 25 times .008 ot o millin'ieter, or 25 times .000315 of un inch. Therefore trom the reudiniro'f .5 of un inch, the product of 25 times `000315, which is .007557 is to loe de- The final residing therefore, correct 'up to the thousundths, will he .4921-25 of; un inch.

The thimlole graduation is divided into 20 equal parts and the readings from the thirn# hle ure directly udded to thereudings token from the longitudinnl seule. ln computing the readings to the correct figure, thelonritudinul' `reedings ore `again multiplied hy .020, odded'thereto istherondine` 'frointhe thimhle, und subtracted from this sum is the product of the number of visible srruduations times the Acompensating 'factor'.OQOll. Thus, tor insta/nce, when the thiinhle grade nation 8 co-incides with the indicator line of the longitudinal scale after lia-ving passed the mark of the inch graduation, the reading is computed as follows times .020 gives .5 of an inch. Added thereto is the thimble reading .008, which gives the sum of .50S and subtracted from this sum `is the product of 25 times .000315, which is .007875, giving the correct reading of .500 of an inch.

Corresponding with this inch reading, the millimeter reading is 12.7 kwhich means that this millimeter reading is equal to 1/2 inch. The millimeter readings are taken as followsz-Tlie thimble being divided into 20 equal parts, it is necessary, in order to obtain thousandths of a millimeter, to divide the thimble readings by Ll0, giving the propel' 1/1000 millimeter reading;

Due to the pitch of the spindle screw, the spindle, and thus the thimble has to make two complete revolutions of 300 degrees be- ",fore the spindle moves a` complete millimeter in longitudinal direction. lVhen,

therefore, lmillimeter readings are taken before the thimble has reached the first half of a millimeter, the procedure is as follows :-For example, the thimble uncovers 10 millimeter graduations and the first half of the 11th millimeter graduation. Assuming that thethimbie graduation 5 appears to coincide with the indicator line of the longitudinal scale, the readings will be 10 millimeters, plus the result of 5 divided by 40, which is .125. rlfhe complete reading therefore will be 10.125 mm.

1n taking measurements when the tl'iimble has passed the second half of the millimeter graduation, .5 is added to the thimble reading, thus when, for instance, the thimble has passed the one-half millimeter mark (which is equivalent to the inch division of the sleeve graduation) and the 5th thimble graduation appears to coincide with. the longitudinal indicator line, the readings will be 10 millimeters, plus .5 millimeter, plus the result of the division 5 through L10 which is .125. The complete reading therefore will be 10.625.

From the above explanation, it will be seen that the inch readings, accurate to thousandths of an inch, and millimeter readings `accurate to .025 of a millimeter, may be talren kby my instrument simultaneously.

One of the objects of my invention is a Vmicrometer provided with means for simultaneouslytaking readings in a plurality of standards.

readings in such standards.

A further object of my invention is to provide in such micrometer, means for line 3 3 of Fig. 1.

facilitating locking my device, in any desired position during the period of taking readings and without in any way impairing the alinement of the micrometer spindle.

Affurther object of my invention is to provide within such locking means, a friction member adapted to uniformly, and at all points of its contacting surface, exerta radially inward pressure against the spindle without. in any way affecting the alinement of the latter.

A further object of my invention is to provide dust proofing means for preventing foreign matter from entering the spindle bearings and the said locking means.

The foregoing and further objects will be more fully apparent from the following description and the accompanying drawing, forming a part of this specification, and in which Fig. 1 represents a side elevation of one preferred form of a micrometer equipped with my graduations.

F 2 is an end elevation of my invention.

Fig. 3 is a cross sectional view taken on Fig. 4 is a detail view of my locking or friction member.

Fig. 5 is an end view thereof.

Fig. 6 is a detail view of the closing cap of my dust proofing arrangement.

Fig. 7 is the ring member of my dust prooliug arrangement.

lFigs. S, 9, and 10 are diagrams illustrating the methods of taking readings mentioned above.

Referring to the drawings, numeral 10 denotes the frame of my device, upon which faces are provided conversion tables, for converting fractions of inches into millimeters. n

The frame as shown in Fig. 1 has an anvil arm 11 provided with a flat surface, indicated at 12, adapted for taking depth measurements, as will be explained later.

The anvil 13 is provided with a threaded extension 14; for adjustment of the anvil in longitudinal direction. Its position is thus fixed by a clamping screw 15. The anvil is drilled longitudinally as indicated at 16 to receive a steel rod 17, which abuts wtitll the spindle of the micrometer. i

The other leg of the fra-me is enlarged at 18 and possesses two spindle bearing ex tensions 19A and 20 respectively. Extending from bearing extension 19 is a barrel or sleeve 21, provided with an internal thread 2o of a half millimeters pitch. The sleeve is split at 23 and reduced at 24, the reduced portion of whichis externally threaded at to receive an adjusting screw 26 for taking care of the wear in internal thread 22.

ldlngaging thread 22 is a threaded portion 27 of spindle 28 the free end of which associated with a thimble 29 terminating in tif) a ratchet arrangement indicated at 30. The latterserves for assuring the operator, when taking; measurements to exert at all times the same degree of pressure upon the object to be measured.

ri'he enlarged end of sleeve 2l is cut out as to coincide and interlock With the corresponding shapes 3l of member' 32.

The intermediate member is reduced and threaded at S3 and provided with a. resilient asher 34, covering` the free threads. Engaging these threads at the ei:- treme end of the reduced portion of intermediate member 32 is the knurled annular' enlargement 35 of closing member 3G pro` vided with. a tapered inner aperture 37, adaptedv to engage the beveled outer surface of friction member 38, as shoivn in detail in Figs. il and T his friction member possesses an annular opening' 39 and is split into a plurality of uniform sections i-(l by incisions all and l alternately open at the opposite ends of' the friction membera as clearly seen in lli-eg. 4.. Extending' from its reduced end is la lug 4:3, engaging a. recess 4:4 provided in the intermediate member 82.

By means of this lug held in the recess, the friction member is prevented from turnine' when the closing or clamping' member ltlis revolved and moves upon the conical outer surface of the friction member in the direction toward or from bearing eXtension 9.0.

The spindle QS lodged Within bearing; #l5 of bearing extension 19, and bearing` tto in bearing extension 20. Adjacent to the latter bearing', an annular recess 47 is provided iu bearing extension Q() for" receiving a closing member or cap 48. shown in detail in Fig. 6.

rlhis cap consists of a ring shaped portion lll). and extending therefrom is acylindrical portion tapered toward its edge at 5l and divided by a plurality of slots .532 into sections.

dit the outer surface of the cylindrical extension 50 is a bead 53, adapted to en* nage a ,cjroove 54, provided in the annular recess lt7 of bearing; extension 20.

The space enclosed by the cylindrical portion 50 df the cap, the cylindrical surface ot ieanindle the bearing Q6 and the ring portion l5) of the cap is filled ivith packing; material 55.j which is compressed by inserting the cap into recess a7. In orderto prevent dust from entering` the space between closing;- member 3G and bearing extension 20, the latter is recessed at 56 for providing a seat for ring; 57 extending over the reduced portion of closing member 3G.

rlhe extending,` port-ion of the ring is internally threaded or corrugated, as indicated at 58. ing); the itirst of the grooves in the ring Will, till the latter and prevent other foreign matter from reaching the space 'between bear-Vk ine; extension 20 and closing member 36.

The caliper as shown 1n the drawing may be used for both depth n'ieasurements and ordinary surface n'ieasurements, for which reason the ejraduations upon the barrel or sleeve may be read in either' right or left hand direction.

vThe scale of multiple pgraduations has a single indicator line 59 co-operiti'ngl with `the thimble graduation provided on the beveled portion GO of .the thimble.

In order to facilitate taking;v readings in both inch and millimeter standards, on the surface of the thiinblesuccessive steps in the manner of takingreadings may be imprinted7 together With the compensation factor. i f

The operation of the lockingor clamping' device is the subject matter of another application.

to' apply my principle to any existing or newly designed micrometer, and to make such improvements as are deemed necessary for various employinents of my instrument.

Having thus described my invention, l claim:-v

n a micrometer. for taking simultaneously readings in various standards, said micrometer composed of a spindle provided with a thread of a pitch equal to one half millimeter.y a sleeve having a correspondiup; thread eng ging the spindle, a double. graduated longitudinal scale provided upon said sleeve and having' a common indicator line, one ,frraduation being in milliimzters.y the other in substantially one liftieth parts of an inch, a thimble associated with said spindle and telescopine with saidsleeve, and havine circumferential graduation of twenty lines, adapted to co-operate with said scale and said indicator line in tak# ingr millimeter and inch readingsat one setting; of said thin'ible.

Signed at New York in the county of New York and State of New York this. 31st day of August A. D. 1921.

LOUIS C. CRESCIO.

Any dust or foreign matter enter? 

